SPARQL1 - · PDF fileRemove the results of PAT2 from the results of PAT1 PAT1 minus {PAT2} 35...

SPARQL1.1

[email protected]

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SPARQL 1.1

1. Overview

2. Query

3. Update

4. Protocol (WSDL 2.0)

5. Service Description (as an RDF Graph)

6. Uniform HTTP Protocol for Managing RDF Graphs

7. Entailment Regimes

8. Test Cases

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Update

Defines an update language for RDF graphs.

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UpdatePREFIX dc: <http://purl.org/dc/elements/1.1/>

INSERT DATA

{ <http://example/book3> dc:title "A new book" ;

dc:creator "A.N.Other" .

}

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Update

PREFIX foaf: <http://xmlns.com/foaf/0.1/>

WITH <http://example/addresses>

DELETE { ?person foaf:firstName 'Bill' }

INSERT { ?person foaf:firstName 'William' }

WHERE

{ ?person a foaf:Person .

?person foaf:firstName 'Bill'

}

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Protocol: WSDL 2.0

Defines an abstract interface and HTTP bindings for a protocol to issue SPARQL Query and SPARQL Update statements against a SPARQL endpoint.

It uses WSDL 2.0 to describe a means for conveying SPARQL queries to an SPARQL query processing service and returning the query results to the entity that requested them

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Service Description: an RDF Graph

Defines a vocabulary and discovery mechanism for describing the capabilities of a SPARQL endpoint accessible by SPARQL Protocol.

SPARQL services made available via the SPARQL Protocol SHOULD return a service description document at the service URL.

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Service Description

This service description SHOULD be made available in an RDF serialization, and MAY be provided embedded in HTML by RDFa

It is an RDF graph that describes the service (e.g. it’s default graph, named graphs, support for 1.0, 1.1, Update, etc.)

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HTTP Protocol

Describes the use of the HTTP protocol for managing named RDF graphs on an HTTP server.

Binding of PUT, GET, POST, etc.

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Entailment Regime

Defines conditions under which SPARQL queries can be used with entailment regimes such as RDF, RDF Schema, OWL, or RIF.

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SPARQL 1.1 Query Language

Project Expression

Aggregates

Property Path

New statements

Minus, Exists

Subquery

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Project Expression

Return the result of an expression

select * (ext:price(?doc) as ?price)

where {

?x rdf:type c:Document

?x c:author ?a

}

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New filters

coalesce(?x, ?y, 10): return first value that is not an error (such as unbound)

if(?x>10, ?y , ?x+10)

?x in (“alpha”, ?beta, ‘gamma’)

uri(), iri(): create an uri

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New functions

strdt(“12”, xsd:integer): create a literal with a datatype

strlang(“human”, “en”): create a literal with a language tag

bnode() bnode(“id314”) : create a blank node

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Aggregates

select ?x (count(?doc) as ?count) where {

?x c:hasCreated ?doc

}

group by ?x

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Group by

Several arguments

select ?x ?date (count(?doc) as ?count) where {


?doc c:date ?date

}

group by ?x ?date

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Group by + count + order



}

group by ?x

order by desc (count(?doc))

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Having

Additional filter after aggregate



}

group by ?x

having (count(?doc) >= 10)

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Aggregates

min, max, count

sum, avg

group_concat, sample

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Aggregates

Return one result when there is no group by

select (min(?price) as ?min) where {

?x ex:price ?price

}

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Aggregates

Count the number of results

select (count(*) as ?count) where {

?x ex:price ?price

}

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Aggregates

Count number of distinct values

select (count(distinct ?x) as ?count) where {

?x ex:price ?price

}

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Exercise

Find the number of persons member of an organization and who are not author of any document

Find in which organization there is the most persons that are not author of any document

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Exercise

select * (count(?x) as ?count)

where {

?x ex:member ?org

filter(?org = <O>)

optional {?x ex:author ?doc}

filter(!bound(?doc))

}

group by ?org

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Exercise

select * (count(?x) as ?count)

where {

?x ex:member ?org

optional {?x ex:author ?doc}

filter(!bound(?doc))

}

group by ?org

order by desc(?count)

limit 1

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Property Path

Path of length more than one between resources

xxx member yyy include zzz author ttt

select * where {

xxx member/include/author ttt

}

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Property Path

xxx rdf:first aaa

xxx rdf:rest yyy rdf:first bbb

xxx rdf:rest yyy rdf:rest zzz rdf:first ccc

Zero or more rest followed by one first : rest* first

select ?val where {

xxx rdf:rest*/rdf:first ?val

}

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Property Path Expression Operators

/ : sequence

| : alternative

+ : one or several

* : zero or several

? : optional

^ : inverse

! : negation

{min,max} : variable length path

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Property Path: Reverse

?x ^ex:prop ?y ::=

?y ex:prop ?x

?x ^EXP ?y ::=

?y EXP ?x

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Property Path: Negation

?x ! ex:prop ?y

All properties but ex:prop

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Property Path: Variable length

?x rdfs:subClassOf{1,5} ?y

?x rdfs:subClassOf{,5} ?y

?x rdfs:subClassOf{1,} ?y

?x rdfs:subClassOf{5} ?y

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Negation

Two patterns:

Minus

Not Exists

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MINUS

Remove the results of PAT2 from the results

of PAT1

PAT1 minus {PAT2}

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MINUS

Remove from the member of org the

resources whose name is ‘Olivier’

select * where {

?x c:memberOf ?org

minus {?x c:name ‘Olivier’}

}

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MINUS

PAT1 minus {PAT2}

Remove results that are compatible: same variables have

same values

when there is at least one common variable

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MINUS: remove nothing

select * where {

?x c:memberOf ?org

minus {?y c:name ‘Olivier’}

}

Remove results that are compatible (same variables have

same values) when there is at least one common

variable

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(NOT) EXISTS

Test (absence) presence of pattern in RDF

Graph

PAT1 . filter(! exists {PAT2})

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NOT EXISTS

?x c:memberOf ?org .

filter(! exists {?x c:author ?doc })

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Minus vs Exists

Same results:


filter(! exists {?x c:author ?doc })


minus {?x c:author ?doc }

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Minus vs Exists

Different results:


filter(! exists {?y c:author ?doc })


minus {?y c:author ?doc }

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Quiz


minus {ex:a c:memberOf ex:b}

Does it return:

ex:a c:memberOf ex:b

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Sub Query: Nested Query

Find properties of the cheapest car

select * where {

{select (min(?price) as ?min) where {

?car ex:hasPrice ?price}

}

?car ex:hasPrice ?min

?car ?p ?val

}

SPARQL1 - · PDF fileRemove the results of PAT2 from the results of PAT1 PAT1 minus {PAT2} 35...

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